JP2022037314A - Image forming apparatus - Google Patents

Image forming apparatus Download PDF

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Publication number
JP2022037314A
JP2022037314A JP2020141383A JP2020141383A JP2022037314A JP 2022037314 A JP2022037314 A JP 2022037314A JP 2020141383 A JP2020141383 A JP 2020141383A JP 2020141383 A JP2020141383 A JP 2020141383A JP 2022037314 A JP2022037314 A JP 2022037314A
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Japan
Prior art keywords
sheet
transfer
rotating body
guide member
transport
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Japanese (ja)
Inventor
峻太郎 手塚
Shuntaro Tezuka
正典 山縣
Masanori Yamagata
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Canon Inc
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Canon Inc
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Priority to JP2020141383A priority Critical patent/JP2022037314A/en
Priority to US17/404,043 priority patent/US11619902B2/en
Publication of JP2022037314A publication Critical patent/JP2022037314A/en
Pending legal-status Critical Current

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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/65—Apparatus which relate to the handling of copy material
    • G03G15/6529—Transporting
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/65—Apparatus which relate to the handling of copy material
    • G03G15/6555—Handling of sheet copy material taking place in a specific part of the copy material feeding path
    • G03G15/6558—Feeding path after the copy sheet preparation and up to the transfer point, e.g. registering; Deskewing; Correct timing of sheet feeding to the transfer point
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/14—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base
    • G03G15/16—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base of a toner pattern, e.g. a powder pattern, e.g. magnetic transfer
    • G03G15/1605—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base of a toner pattern, e.g. a powder pattern, e.g. magnetic transfer using at least one intermediate support

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Electrostatic Charge, Transfer And Separation In Electrography (AREA)
  • Paper Feeding For Electrophotography (AREA)
  • Delivering By Means Of Belts And Rollers (AREA)
  • Feeding Of Articles By Means Other Than Belts Or Rollers (AREA)

Abstract

To provide an image forming apparatus that can reduce an image defect and conveyance failure regardless of the rigidity of a sheet.SOLUTION: An image forming apparatus comprises: a rotating body that is movable between a first position at which it projects toward a conveyance path and a second position at which it is separated from a guide member compared with the first position; and an urging unit that urges the rotating body toward the first position. An urging force of the urging unit is set such that when a first sheet having first rigidity is conveyed over a conveying unit and a transfer unit, the rotating body is located at the first position, and when a second sheet having second rigidity larger than the first rigidity is conveyed over the conveying unit and the transfer unit, the rotating body is pressed by the second sheet and located at the second position.SELECTED DRAWING: Figure 5

Description

本発明は、シートに画像を形成する画像形成装置に関する。 The present invention relates to an image forming apparatus that forms an image on a sheet.

従来、転写ニップにおいて像担持体からシートにトナー像を転写する転写ローラと、転写ニップに向けてシートを搬送するレジストローラ対と、を有するプリンタが提案されている（特許文献１参照）。レジストローラ対と転写ニップとの間には、シートを案内する上搬送ガイド及び下搬送ガイドが設けられており、上搬送ガイドには、ガイドコロ及び補助ガイド部が設けられている。レジストローラを通過したシートの先端部は、ガイドコロに沿って搬送され、シートの後端部は、ガイドコロを通過した後、補助ガイド部に沿って搬送される。 Conventionally, a printer having a transfer roller that transfers a toner image from an image carrier to a sheet in a transfer nip and a resist roller pair that conveys a sheet toward the transfer nip has been proposed (see Patent Document 1). An upper transfer guide and a lower transfer guide for guiding the sheet are provided between the resist roller pair and the transfer nip, and the upper transfer guide is provided with a guide roller and an auxiliary guide portion. The front end portion of the sheet that has passed through the resist roller is conveyed along the guide roller, and the rear end portion of the sheet is conveyed along the auxiliary guide portion after passing through the guide roller.

特開２０１７－７８７８８号公報Japanese Unexamined Patent Publication No. 2017-78788

ところで、特にシート搬送速度や画像形成速度が速いプリンタにおいては、転写ニップの手前でシートのバタつきや振動が生じた際に、シートに転写される画像に乱れが生じてしまうことがあった。 By the way, particularly in a printer having a high sheet transport speed and an image forming speed, when the sheet flutters or vibrates in front of the transfer nip, the image transferred to the sheet may be disturbed.

上記特許文献１に記載のプリンタは、ガイドコロ及び補助ガイド部が上搬送ガイドのシート搬送方向における上流端部に設けられているため、ガイドコロ及び補助ガイド部と、転写ニップと、の間に距離があった。このため、転写ニップ近傍でのシートの挙動を抑えることができず、シートのバタつきが発生し、画像不良が発生してしまう。また、シートの拘束力を高めてシートのバタつきを抑えようとすると、搬送抵抗が大きくなって搬送不良を起こしてしまうという課題があり、これらシートの拘束力と搬送抵抗は、シートの剛性によって適切な値が異なる。 In the printer described in Patent Document 1, since the guide roller and the auxiliary guide portion are provided at the upstream end portion of the upper transport guide in the sheet transport direction, the guide roller and the auxiliary guide portion are between the transfer nip. There was a distance. Therefore, the behavior of the sheet in the vicinity of the transfer nip cannot be suppressed, the sheet flutters, and image defects occur. Further, if an attempt is made to increase the binding force of the sheet to suppress the fluttering of the sheet, there is a problem that the transfer resistance becomes large and a transfer failure occurs. The binding force and the transfer resistance of these sheets depend on the rigidity of the sheet. Appropriate values are different.

そこで、本発明は、シートの剛性に拘わらず画像不良及び搬送不良を低減できる画像形成装置を提供することを目的とする。 Therefore, an object of the present invention is to provide an image forming apparatus capable of reducing image defects and transport defects regardless of the rigidity of the sheet.

本発明は、画像形成装置において、静電潜像を担持する像担持体と、前記像担持体に担持された前記静電潜像をトナー像として現像する現像部と、前記像担持体との間に転写部を形成し、前記像担持体に担持された前記トナー像を前記転写部においてシートに転写する転写部材と、前記転写部に向けてシートを搬送する搬送部と、前記搬送部と前記転写部との間でシートが通過する搬送路に対して前記像担持体と同じ側に配置され、前記搬送部によって搬送されるシートを前記転写部に向けて案内するガイド部材と、前記ガイド部材に対向するように配置されると共に、前記搬送路に突出した第１位置と、前記第１位置よりも前記ガイド部材から離れた第２位置と、の間で移動可能な回転体であって、前記搬送部によって搬送されるシートに対して従動回転する回転体と、前記回転体を前記第１位置に向けて付勢する付勢部と、を備え、前記付勢部は、第１の剛性を有する第１シートが前記搬送部及び前記転写部に跨って搬送されている際に、前記回転体が前記第１位置に位置し、前記第１の剛性よりも大きい第２の剛性を有する第２シートが前記搬送部及び前記転写部に跨って搬送されている際に、前記回転体が前記第２シートに押圧されて前記第２位置に位置するように、付勢力が設定される、ことを特徴とする。 The present invention comprises an image carrier that supports an electrostatic latent image, a developing unit that develops the electrostatic latent image supported on the image carrier as a toner image, and the image carrier in an image forming apparatus. A transfer member that forms a transfer portion between them and transfers the toner image carried on the image carrier to a sheet in the transfer portion, a transport portion that transports the sheet toward the transfer portion, and the transport unit. A guide member arranged on the same side as the image carrier with respect to the transport path through which the sheet passes between the transfer section and guiding the sheet transported by the transfer section toward the transfer section, and the guide. A rotating body that is arranged so as to face the member and can move between a first position protruding into the transport path and a second position that is farther from the guide member than the first position. A rotating body that is driven to rotate with respect to a sheet conveyed by the transport unit, and an urging unit that urges the rotating body toward the first position, and the urging unit is the first. When the first sheet having rigidity is transported across the transport portion and the transfer portion, the rotating body is located at the first position and has a second rigidity larger than the first rigidity. When the second sheet is transported across the transport section and the transfer section, the urging force is set so that the rotating body is pressed against the second sheet and is positioned at the second position. It is characterized by that.

本発明によると、シートの剛性に拘わらず画像不良及び搬送不良を低減できる。 According to the present invention, image defects and transport defects can be reduced regardless of the rigidity of the sheet.

本実施の形態に係るプリンタを示す全体概略図。The whole schematic which shows the printer which concerns on this embodiment. 転写前ガイド機構を示す断面図。Sectional drawing which shows the guide mechanism before transfer. コロ部材を示す斜視図。The perspective view which shows the roller member. 第１の剛性を有する第１シートが搬送される際のコロ部材の動作を示す断面図。FIG. 3 is a cross-sectional view showing the operation of a roller member when a first sheet having the first rigidity is conveyed. 第２の剛性を有する第２シートが搬送される際のコロ部材の動作を示す断面図。FIG. 2 is a cross-sectional view showing the operation of a roller member when a second sheet having a second rigidity is conveyed.

〔全体構成〕
画像形成装置としてのプリンタ１は、モノクロのトナー像を形成する電子写真方式のレーザビームプリンタである。なお、以下の説明において、シートＳとは、プリンタ１によって画像が形成されるものであって、例えば、紙、ＯＨＴシート等が含まれ、コート紙、薄紙、普通紙及び厚紙等の複数の種類のシートも含まれる。 〔overall structure〕
The printer 1 as an image forming apparatus is an electrophotographic laser beam printer that forms a monochrome toner image. In the following description, the sheet S is an image formed by the printer 1, and includes, for example, paper, an OHT sheet, and a plurality of types such as coated paper, thin paper, plain paper, and thick paper. Sheet is also included.

プリンタ１は、図１に示すように、積載されたシートを給送するシート給送部４０と、シート給送部４０によって給送されたシートを搬送すると共にシートに画像を形成する画像形成部５０と、を有している。また、プリンタ１は、シートに転写された画像を定着させる定着器９と、シートを排出トレイ１１に排出可能な排出ローラ対１０と、を有している。 As shown in FIG. 1, the printer 1 has a sheet feeding unit 40 that feeds a loaded sheet, and an image forming unit that conveys a sheet fed by the sheet feeding unit 40 and forms an image on the sheet. It has 50 and. Further, the printer 1 has a fixing device 9 for fixing the image transferred to the sheet, and a discharge roller pair 10 capable of discharging the sheet to the discharge tray 11.

プリンタ１に画像形成ジョブが出力されると、プリンタ１に接続された外部のコンピュータ等から入力された画像情報に基づいて、画像形成部５０による画像形成プロセスが開始される。画像形成部５０は、後述する転写前ガイド機構２０と、レーザスキャナ７と、感光ドラム５と、帯電ローラ５ａ（図２参照）と、現像ローラ８と、転写ローラ６と、を有している。感光ドラム５、帯電ローラ５ａ及び現像ローラ８は、一体となって交換できるようにカートリッジ化されている。感光ドラム５及び転写ローラ６は、転写部としての転写ニップＴ１を形成している。 When the image forming job is output to the printer 1, the image forming process by the image forming unit 50 is started based on the image information input from an external computer or the like connected to the printer 1. The image forming unit 50 includes a pre-transfer guide mechanism 20, a laser scanner 7, a photosensitive drum 5, a charging roller 5a (see FIG. 2), a developing roller 8, and a transfer roller 6, which will be described later. .. The photosensitive drum 5, the charging roller 5a, and the developing roller 8 are integrated into a cartridge so that they can be replaced. The photosensitive drum 5 and the transfer roller 6 form a transfer nip T1 as a transfer portion.

レーザスキャナ７は、入力された画像情報に基づいて、感光ドラム５に向けてレーザ光を照射する。このとき、像担持体としての感光ドラム５は、帯電ローラ５ａにより予め帯電されており、レーザ光が照射されることで感光ドラム５上に静電潜像が形成される。その後、現像部としての現像ローラ８によりこの静電潜像が現像され、感光ドラム５上にモノクロのトナー像が形成される。 The laser scanner 7 irradiates the photosensitive drum 5 with a laser beam based on the input image information. At this time, the photosensitive drum 5 as the image carrier is precharged by the charging roller 5a, and the electrostatic latent image is formed on the photosensitive drum 5 by being irradiated with the laser beam. After that, the electrostatic latent image is developed by the developing roller 8 as a developing unit, and a monochrome toner image is formed on the photosensitive drum 5.

上述の画像形成プロセスに並行して、シート給送部４０からシートＳが給送される。シート給送部４０は、プリンタ１の装置本体１Ａに対して引出し及び装着可能なカセット２と、給送ローラ４１と、分離ローラ対４２と、を有している。カセット２に収容されたシートＳは、給送ローラ４１によって給送され、給送ローラ４１によって給送されたシートＳは、分離ローラ対４２によって１枚ずつに分離される。 In parallel with the image forming process described above, the sheet S is fed from the sheet feeding unit 40. The sheet feeding unit 40 has a cassette 2 that can be pulled out and mounted on the apparatus main body 1A of the printer 1, a feeding roller 41, and a separation roller pair 42. The sheet S housed in the cassette 2 is fed by the feeding roller 41, and the sheets S fed by the feeding roller 41 are separated one by one by the separating roller pair 42.

なお、カセット２には、シートを支持可能かつ昇降可能な中板を設けてもよく、例えば画像形成ジョブが入力されることによって中板を上昇させ、中板に支持されたシートと給送ローラ４１とを接触させてもよい。また、分離ローラ対４２は、ローラ対の一方がパッド等でもよく、トルクリミッタ方式やリタードローラ方式等を適用できる。 The cassette 2 may be provided with a middle plate that can support the sheet and can be raised and lowered. For example, the middle plate is raised by inputting an image forming job, and the sheet and the feeding roller supported by the middle plate are provided. It may be brought into contact with 41. Further, as the separation roller pair 42, one of the roller pairs may be a pad or the like, and a torque limiter method, a retard roller method or the like can be applied.

分離ローラ対４２によって１枚ずつに分離されたシートＳは、搬送部としての搬送ローラ対４によって搬送される。なお、シートＳの斜行を補正可能なレジストレーションローラ対から構成されてもよい。シートＳは、停止状態のレジストレーションローラ対のニップに突き当たることで斜行が補正される。レジストレーションローラ対は、転写ニップＴ１におけるトナー像の転写タイミングに合わせて、シートＳを搬送する。 The sheets S separated one by one by the separation roller pair 42 are conveyed by the transfer roller pair 4 as the transfer unit. It may be composed of a pair of registration rollers capable of correcting the skew of the sheet S. The sheet S abuts on the nip of the resist roller pair in the stopped state to correct the skew. The registration roller pair conveys the sheet S in accordance with the transfer timing of the toner image in the transfer nip T1.

搬送ローラ対４によって搬送されたシートＳは、転写前ガイド機構２０によって転写ニップＴ１に案内される。シートＳには、転写部材としての転写ローラ６に印加された静電的負荷バイアスによって、転写ニップＴ１において感光ドラム５上のトナー像が転写される。感光ドラム５上に残った残トナーは、不図示のクリーニングブレードによって回収される。トナー像が転写されたシートＳは、定着器９によって所定の熱及び圧力が付与されて、トナーが溶融固着（定着）される。定着器９を通過したシートＳは、排出ローラ対１０によって排出トレイ１１に排出される。 The sheet S conveyed by the transfer roller pair 4 is guided to the transfer nip T1 by the pre-transfer guide mechanism 20. The toner image on the photosensitive drum 5 is transferred to the sheet S at the transfer nip T1 by the electrostatic load bias applied to the transfer roller 6 as the transfer member. The residual toner remaining on the photosensitive drum 5 is recovered by a cleaning blade (not shown). Predetermined heat and pressure are applied to the sheet S on which the toner image is transferred by the fixing device 9, and the toner is melt-fixed (fixed). The sheet S that has passed through the fuser 9 is discharged to the discharge tray 11 by the discharge roller pair 10.

［転写前ガイド機構］
次に、図２及び図３を用いて、転写前ガイド機構２０の構成について説明する。転写前ガイド機構２０は、図２に示すように、第１ガイド部材２１と、第２ガイド部材２２と、第３ガイド部材２８と、コロ部材２３と、支持部材２４と、加圧バネ２５と、を有する。 [Pre-transfer guide mechanism]
Next, the configuration of the pre-transfer guide mechanism 20 will be described with reference to FIGS. 2 and 3. As shown in FIG. 2, the pre-transfer guide mechanism 20 includes a first guide member 21, a second guide member 22, a third guide member 28, a roller member 23, a support member 24, and a pressure spring 25. , Have.

第２ガイド部材２２及び第３ガイド部材２８は、ガイド部材としての第１ガイド部材２１に対向するように配置され、これら第１ガイド部材２１、第２ガイド部材２２及び第３ガイド部材２８によって、搬送路２６が形成される。搬送ローラ対４と転写ニップＴ１との間において、シートＳは搬送路２６を通過する。 The second guide member 22 and the third guide member 28 are arranged so as to face the first guide member 21 as a guide member, and are provided by the first guide member 21, the second guide member 22, and the third guide member 28. The transport path 26 is formed. The sheet S passes through the transfer path 26 between the transfer roller pair 4 and the transfer nip T1.

第１ガイド部材２１は、搬送路２６に対して感光ドラム５と同じ側に配置され、第２ガイド部材２２、第３ガイド部材２８、コロ部材２３、支持部材２４及び加圧バネ２５は、搬送路２６に対して転写ローラ６と同じ側に配置されている。回転体としてのコロ部材２３は、第１ガイド部材２１に対向するように配置されると共に、シート搬送方向ＣＤにおいて第２ガイド部材２２と第３ガイド部材２８との継ぎ目部分近傍に配置されている。コロ部材２３は、搬送ローラ対４によって搬送されるシートＳに対して従動回転する。第１ガイド部材２１は、コロ部材２３から離れる方向に湾曲した湾曲部２１ｂを有しており、第２ガイド部材２２は、シートを転写ニップＴ１よりもやや感光ドラム５寄りに案内する。 The first guide member 21 is arranged on the same side as the photosensitive drum 5 with respect to the transport path 26, and the second guide member 22, the third guide member 28, the roller member 23, the support member 24, and the pressure spring 25 are conveyed. It is arranged on the same side as the transfer roller 6 with respect to the path 26. The roller member 23 as a rotating body is arranged so as to face the first guide member 21, and is arranged in the vicinity of the joint portion between the second guide member 22 and the third guide member 28 in the sheet transport direction CD. .. The roller member 23 is driven to rotate with respect to the sheet S conveyed by the transfer roller pair 4. The first guide member 21 has a curved portion 21b curved in a direction away from the roller member 23, and the second guide member 22 guides the sheet slightly closer to the photosensitive drum 5 than the transfer nip T1.

このため、搬送路２６は、緩やかなＳ字状に形成され、図２において破線で示すシートＳは、感光ドラム５に沿うような角度で転写ニップＴ１に進入する。よって、シートＳが感光ドラム５に突入する際の衝撃を抑制し、シートＳの先端によって感光ドラム５にダメージが発生することを低減できる。また、感光ドラム５からシートＳへトナーを転写する際のトナーの散りを低減できる。 Therefore, the transport path 26 is formed in a gentle S shape, and the sheet S shown by the broken line in FIG. 2 enters the transfer nip T1 at an angle along the photosensitive drum 5. Therefore, it is possible to suppress the impact when the sheet S rushes into the photosensitive drum 5, and reduce the occurrence of damage to the photosensitive drum 5 by the tip of the sheet S. Further, it is possible to reduce the scattering of toner when transferring the toner from the photosensitive drum 5 to the sheet S.

第１ガイド部材２１のシート搬送方向ＣＤにおける下流端部には、シートＳに接触可能な接触部２１ａが設けられており、第２ガイド部材２２のシート搬送方向ＣＤにおける下流端部には、シートＳに接触可能な接触部２２ａが設けられている。第１接触部としての接触部２１ａは、シート搬送方向ＣＤにおいてコロ部材２３よりも下流に位置し、第２接触部としての接触部２２ａは、シート搬送方向ＣＤにおいて接触部２１ａと転写ニップＴ１との間に配置されている。 A contact portion 21a that can contact the sheet S is provided at the downstream end portion of the first guide member 21 in the sheet transport direction CD, and a sheet is provided at the downstream end portion of the second guide member 22 in the sheet transport direction CD. A contact portion 22a that can come into contact with S is provided. The contact portion 21a as the first contact portion is located downstream of the roller member 23 in the sheet transport direction CD, and the contact portion 22a as the second contact portion is the contact portion 21a and the transfer nip T1 in the sheet transport direction CD. It is placed between.

支持部材２４は、回動軸２４ａを中心に回動可能に支持されており、コロ部材２３は、支持部材２４の先端部に回転可能に支持されている。回動軸２４ａは、シート搬送方向ＣＤにおいてコロ部材２３よりも上流に配置されている。コロ部材２３は、支持部材２４が回動することで第１位置（図２及び図４に示す位置）と第２位置（図５に示す位置）との間で移動可能に設けられている。コロ部材２３は、第１位置において搬送路２６に突出しており、第２位置において第１位置よりも第１ガイド部材２１から離れている。 The support member 24 is rotatably supported around the rotation shaft 24a, and the roller member 23 is rotatably supported by the tip end portion of the support member 24. The rotation shaft 24a is arranged upstream of the roller member 23 in the sheet transport direction CD. The roller member 23 is provided so as to be movable between the first position (position shown in FIGS. 2 and 4) and the second position (position shown in FIG. 5) by rotating the support member 24. The roller member 23 protrudes into the transport path 26 at the first position, and is farther from the first guide member 21 than the first position at the second position.

コロ部材２３は、支持部材２４が加圧バネ２５に付勢されることによって、第１位置に向けて付勢されており、支持部材２４の回動範囲は、図４に示すように、第１規制部材２７ａ及び第２規制部材２７ｂによって規制されている。コロ部材２３が第１位置に位置する際には、支持部材２４は第１規制部材２７ａに当接しており、コロ部材２３が第２位置に位置する際には、支持部材２４は第２規制部材２７ｂに当接している。付勢部としての加圧バネ２５は、圧縮コイルバネから構成されている。 The roller member 23 is urged toward the first position by urging the support member 24 to the pressure spring 25, and the rotation range of the support member 24 is as shown in FIG. It is regulated by 1 regulatory member 27a and 2nd regulatory member 27b. When the roller member 23 is located at the first position, the support member 24 is in contact with the first regulation member 27a, and when the roller member 23 is located at the second position, the support member 24 is in second regulation. It is in contact with the member 27b. The pressure spring 25 as the urging portion is composed of a compression coil spring.

図３に示すように、コロ部材２３は、シート搬送方向ＣＤに直交する幅方向Ｗにおいて複数並設されている。第３ガイド部材２８は、シートＳを複数のコロ部材２３に向けて案内する複数のリブ２８ａが設けられている。第２ガイド部材２２は、複数のコロ部材２３が搬送路２６へ突出するための複数の開口部２２ｂを有している。なお、複数のコロ部材２３は、１つの支持部材２４に支持されてもよく、コロ部材２３の数と同じ数だけ支持部材２４を設けてもよい。 As shown in FIG. 3, a plurality of roller members 23 are arranged side by side in the width direction W orthogonal to the sheet transport direction CD. The third guide member 28 is provided with a plurality of ribs 28a that guide the seat S toward the plurality of roller members 23. The second guide member 22 has a plurality of openings 22b for the plurality of roller members 23 to project into the transport path 26. The plurality of roller members 23 may be supported by one support member 24, or the number of support members 24 may be the same as the number of roller members 23.

［コロ部材の動作］
次に、剛性の異なる２つのシートが搬送される際の、コロ部材２３の動作について説明する。図４は、第１の剛性を有する第１シートＳ１が搬送される際のコロ部材２３の動作を示す断面図である。図５は、第１の剛性よりも大きい第２の剛性を有する第２シートＳ２が搬送される際のコロ部材２３の動作を示す断面図である。 [Operation of roller member]
Next, the operation of the roller member 23 when two sheets having different rigidity are conveyed will be described. FIG. 4 is a cross-sectional view showing the operation of the roller member 23 when the first sheet S1 having the first rigidity is conveyed. FIG. 5 is a cross-sectional view showing the operation of the roller member 23 when the second sheet S2 having the second rigidity larger than the first rigidity is conveyed.

第１シートＳ１は、例えば薄紙や普通紙が含まれ、薄紙は、例えば５２～６３ｇ／ｍ２の坪量を有し、普通紙は、例えば６４～１０５ｇ／ｍ２の坪量を有する。すなわち、第１シートＳ１は、第１の坪量を有する。第２シートＳ２は、例えば厚紙やコート紙が含まれ、厚紙は、例えば１０６～３００ｇ／ｍ２の坪量を有する。すなわち、第２シートＳ２は、第１の坪量よりも大きい第２の坪量を有する。 The first sheet S1 includes, for example, thin paper or plain paper, the thin paper has a basis weight of, for example, 52 to 63 g / m 2 , and the plain paper has a basis weight of, for example, 64 to 105 g / m 2 . That is, the first sheet S1 has the first basis weight. The second sheet S2 includes, for example, thick paper or coated paper, and the thick paper has a basis weight of, for example, 106 to 300 g / m 2 . That is, the second sheet S2 has a second basis weight larger than the first basis weight.

第１シートＳ１は、図４に示すように、搬送ローラ対４によって搬送され、搬送路２６を通って転写ニップＴ１に案内される。この時、コロ部材２３は、搬送ローラ対４及び転写ニップＴ１に跨って搬送されている第１シートＳ１に接触しており、第１ガイド部材２１に沿って湾曲した第１シートＳ１の反力（コシ）によって押圧される。しかし、第１シートＳ１は、比較的剛性が小さいため、第１シートＳ１の上記反力は、加圧バネ２５の付勢力よりも小さい。 As shown in FIG. 4, the first sheet S1 is conveyed by the transfer roller pair 4 and guided to the transfer nip T1 through the transfer path 26. At this time, the roller member 23 is in contact with the first sheet S1 being conveyed across the transfer roller pair 4 and the transfer nip T1, and the reaction force of the first sheet S1 curved along the first guide member 21. Pressed by (koshi). However, since the first sheet S1 has a relatively small rigidity, the reaction force of the first sheet S1 is smaller than the urging force of the pressure spring 25.

よって、第１シートＳ１は、加圧バネ２５の付勢力に打ち勝ってコロ部材２３を第１位置から第２位置へ向けて押し込むことができず、コロ部材２３は、第１位置に位置している。第１位置に位置するコロ部材２３は、第１シートＳ１が第１ガイド部材２１の接触部２１ａに接触するように、第１シートＳ１を案内している。また、第１シートＳ１は、第２ガイド部材２２の接触部２２ａにも接触している。 Therefore, the first sheet S1 cannot overcome the urging force of the pressure spring 25 and push the roller member 23 from the first position to the second position, and the roller member 23 is located at the first position. There is. The roller member 23 located at the first position guides the first sheet S1 so that the first sheet S1 comes into contact with the contact portion 21a of the first guide member 21. Further, the first sheet S1 is also in contact with the contact portion 22a of the second guide member 22.

すなわち、第１シートＳ１は、第１位置に位置するコロ部材２３及び接触部２１ａ，２２ａによって、第１シートＳ１の厚み方向において挟持され、搬送される際の姿勢が規制される。これにより、第１シートＳ１のバタつきや振動が抑えられて安定したシート搬送が可能となり、画像不良を低減できる。また、第１シートＳ１は、比較的剛性が低いため、第１位置に位置するコロ部材２３及び接触部２１ａ，２２ａによって拘束されても、搬送抵抗が過大にはならず、搬送不良は低減できている。 That is, the first sheet S1 is sandwiched in the thickness direction of the first sheet S1 by the roller member 23 and the contact portions 21a and 22a located at the first position, and the posture when being conveyed is restricted. As a result, fluttering and vibration of the first sheet S1 are suppressed, stable sheet transfer becomes possible, and image defects can be reduced. Further, since the first sheet S1 has a relatively low rigidity, even if it is restrained by the roller member 23 and the contact portions 21a and 22a located at the first position, the transfer resistance does not become excessive and the transfer defect can be reduced. ing.

一方で、第１シートＳ１に比して剛性の高い第２シートＳ２は、図５に示すように、搬送ローラ対４によって搬送され、搬送路２６を通って転写ニップＴ１に案内される。この時、コロ部材２３は、搬送ローラ対４及び転写ニップＴ１に跨って搬送されている第２シートＳ２に接触しており、第１ガイド部材２１に沿って湾曲した第２シートＳ２の反力（コシ）によって押圧される。第２シートＳ２は、比較的剛性が高いため、第２シートＳ２の上記反力は、加圧バネ２５の付勢力よりも大きい。 On the other hand, as shown in FIG. 5, the second sheet S2, which has higher rigidity than the first sheet S1, is conveyed by the transfer roller pair 4 and guided to the transfer nip T1 through the transfer path 26. At this time, the roller member 23 is in contact with the second sheet S2 being conveyed across the transfer roller pair 4 and the transfer nip T1, and the reaction force of the second sheet S2 curved along the first guide member 21. Pressed by (koshi). Since the second seat S2 has a relatively high rigidity, the reaction force of the second seat S2 is larger than the urging force of the pressure spring 25.

よって、第２シートＳ２は、加圧バネ２５の付勢力に打ち勝ってコロ部材２３を第１位置から第２位置に押圧し、コロ部材２３は、第２規制部材２７ｂに突き当たって第２位置に位置している。ところで、コロ部材２３は、コロ部材２３よりもシート搬送方向ＣＤにおいて上流に位置する回動軸２４ａを中心に第１位置から第２位置に揺動する。このため、第２シートＳ２から加わる力でコロ部材２３が回転する方向と、コロ部材２３が回動軸２４ａを中心に揺動する方向と、が一致し、スムーズにコロ部材２３を第２位置へ移動させることができる。 Therefore, the second sheet S2 overcomes the urging force of the pressure spring 25 and presses the roller member 23 from the first position to the second position, and the roller member 23 abuts on the second regulating member 27b and moves to the second position. positioned. By the way, the roller member 23 swings from the first position to the second position about the rotation shaft 24a located upstream of the roller member 23 in the sheet transport direction CD. Therefore, the direction in which the roller member 23 rotates due to the force applied from the second sheet S2 and the direction in which the roller member 23 swings about the rotation shaft 24a coincide with each other, and the roller member 23 is smoothly placed in the second position. Can be moved to.

搬送ローラ対４及び転写ニップＴ１に跨って搬送されている第２シートＳ２は、第２位置に位置するコロ部材２３及び第２ガイド部材２２の接触部２２ａに接触するが、第１ガイド部材２１の接触部２１ａには接触しない。 The second sheet S2, which is conveyed across the transfer roller pair 4 and the transfer nip T1, comes into contact with the contact portion 22a of the roller member 23 and the second guide member 22 located at the second position, but the first guide member 21 Does not come into contact with the contact portion 21a of.

すなわち、第２シートＳ２は、第１シートＳ１のように、コロ部材２３及び接触部２１ａ，２２ａによって、第２シートＳ２の厚み方向において挟持されない。比較的剛性が高い第２シートＳ２は、一般的に第１シートＳ１よりもバタつきが発生し難いため、コロ部材２３及び接触部２１ａ，２２ａによって搬送される際の姿勢が規制されなくとも、画像不良の発生は低減できている。 That is, unlike the first sheet S1, the second sheet S2 is not sandwiched by the roller member 23 and the contact portions 21a and 22a in the thickness direction of the second sheet S2. Since the second sheet S2 having a relatively high rigidity is generally less likely to flutter than the first sheet S1, even if the posture when being conveyed by the roller member 23 and the contact portions 21a and 22a is not regulated, the posture is not restricted. The occurrence of image defects has been reduced.

また、第２シートＳ２は、自身の反力によってコロ部材２３を第２位置に押圧するため、第２シートＳ２の湾曲が少なくなると共に、第１ガイド部材２１の接触部２１ａとは摺擦しない。このため、第２シートＳ２を搬送する際の搬送抵抗を低減でき、搬送抵抗の増大に起因する搬送不良を低減できる。また、コロ部材２３は、第１シートＳ１及び第２シートＳ２に対して従動回転するので、シートがガイド等の固定部材と摺擦する場合に比して、シートの搬送抵抗を更に低減することができる。 Further, since the second sheet S2 presses the roller member 23 to the second position by its own reaction force, the bending of the second sheet S2 is reduced and the second sheet S2 does not rub against the contact portion 21a of the first guide member 21. .. Therefore, the transport resistance at the time of transporting the second sheet S2 can be reduced, and the transport defect due to the increase in the transport resistance can be reduced. Further, since the roller member 23 is driven to rotate with respect to the first sheet S1 and the second sheet S2, the transport resistance of the sheet is further reduced as compared with the case where the sheet rubs against a fixing member such as a guide. Can be done.

以上のように、本実施の形態では、加圧バネ２５の付勢力を、シートＳの剛性に応じてコロ部材２３の位置が変化するように設定した。具体的には、第１の剛性を有する第１シートＳ１が搬送される際には、コロ部材２３は第１位置に位置し、第１の剛性よりも大きい第２の剛性を有する第２シートＳ２が搬送される際には、コロ部材２３は第２シートＳ２の反力によって第２位置に位置する。 As described above, in the present embodiment, the urging force of the pressure spring 25 is set so that the position of the roller member 23 changes according to the rigidity of the seat S. Specifically, when the first sheet S1 having the first rigidity is conveyed, the roller member 23 is located at the first position, and the second sheet having a second rigidity larger than the first rigidity. When S2 is conveyed, the roller member 23 is positioned at the second position by the reaction force of the second sheet S2.

このように加圧バネ２５の付勢力を決定することで、シートの剛性に拘わらず、シートのバタつきを抑えると共に搬送不良を低減できるため、画像不良及び搬送不良を低減できる。また、支持部材２４の回動軸２４ａがシート搬送方向ＣＤにおいてコロ部材２３よりも上流に配置されているので、第２シートＳ２によってコロ部材２３が押圧される際に、スムーズにコロ部材２３を第２位置へ移動させることができる。 By determining the urging force of the pressure spring 25 in this way, fluttering of the seat can be suppressed and transport defects can be reduced regardless of the rigidity of the seat, so that image defects and transport defects can be reduced. Further, since the rotation shaft 24a of the support member 24 is arranged upstream of the roller member 23 in the sheet transport direction CD, when the roller member 23 is pressed by the second sheet S2, the roller member 23 is smoothly pressed. It can be moved to the second position.

＜その他の実施形態＞
上述した実施の形態では、コロ部材２３の第２位置は、支持部材２４が第２規制部材２７ｂに突き当たることで規定されていたが、これに限定されない。例えば、第２規制部材２７ｂを省いてもよい。 <Other embodiments>
In the above-described embodiment, the second position of the roller member 23 is defined by the support member 24 abutting on the second regulating member 27b, but is not limited thereto. For example, the second regulating member 27b may be omitted.

また、図５に示すように、第２シートＳ２が搬送される際には、コロ部材２３は、支持部材２４が第２規制部材２７ｂに突き当たる第２位置に位置していたが、これに限定されない。例えば、第２シートＳ２が搬送される際に、支持部材２４は、第１規制部材２７ａ及び第２規制部材２７ｂの両方に当接しない位置に位置してもよい。すなわち、加圧バネ２５の付勢力は、第１シートＳ１の反力によってはコロ部材２３が第１位置から移動せず、第２シートＳ２の反力によってはコロ部材２３が第１位置から移動するように設定されていればよい。 Further, as shown in FIG. 5, when the second sheet S2 is conveyed, the roller member 23 is located at the second position where the support member 24 abuts on the second regulating member 27b, but the limitation is limited to this. Not done. For example, when the second sheet S2 is conveyed, the support member 24 may be located at a position where it does not abut on both the first regulation member 27a and the second regulation member 27b. That is, as for the urging force of the pressure spring 25, the roller member 23 does not move from the first position due to the reaction force of the first sheet S1, and the roller member 23 moves from the first position due to the reaction force of the second sheet S2. It suffices if it is set to do.

また、上述した実施の形態では、搬送ローラ対４及び転写ニップＴ１に跨って搬送されている第２シートＳ２は、第１ガイド部材２１の接触部２１ａに接触していないが、これに限定されない。例えば、第２シートＳ２は、コロ部材２３及び接触部２１ａ，２２ａによって強く拘束されなければ、接触部２１ａに対して接触してもよい。 Further, in the above-described embodiment, the second sheet S2 transported across the transport roller pair 4 and the transfer nip T1 is not in contact with the contact portion 21a of the first guide member 21, but is not limited thereto. .. For example, the second sheet S2 may come into contact with the contact portion 21a as long as it is not strongly restrained by the roller member 23 and the contact portions 21a and 22a.

また、上述した実施の形態では、支持部材２４の回動軸２４ａが、シート搬送方向ＣＤにおいてコロ部材２３よりも上流に配置されているが、コロ部材２３よりも下流に配置されていてもよい。 Further, in the above-described embodiment, the rotation shaft 24a of the support member 24 is arranged upstream of the roller member 23 in the sheet transport direction CD, but may be arranged downstream of the roller member 23. ..

また、上述した実施の形態では、コロ部材２３は、円筒形状のローラによって構成されていたが、これに限定されない。例えば、コロ部材２３は、球やベルトによって構成されてもよい。 Further, in the above-described embodiment, the roller member 23 is composed of a cylindrical roller, but the roller member 23 is not limited to this. For example, the roller member 23 may be composed of a ball or a belt.

また、上述した実施の形態では、加圧バネ２５に圧縮コイルバネを用いているが、これに限定されない。例えば、加圧バネ２５は、ねじりコイルバネや板バネ等の他の弾性部材を適用してもよい。 Further, in the above-described embodiment, the compression coil spring is used for the pressure spring 25, but the pressure spring 25 is not limited to this. For example, other elastic members such as torsion coil springs and leaf springs may be applied to the pressure spring 25.

また、上述した実施の形態では、感光ドラム５及び転写ローラ６によって転写ニップＴ１が形成されていたが、これに限定されない。例えば、転写ローラ６に代えて、コロナ帯電器を適用してもよく、この場合、転写ニップＴ１は形成されず、転写ローラ６とコロナ帯電器によってシートが転写される部分を転写部とする。 Further, in the above-described embodiment, the transfer nip T1 is formed by the photosensitive drum 5 and the transfer roller 6, but the present invention is not limited to this. For example, a corona charger may be applied instead of the transfer roller 6. In this case, the transfer nip T1 is not formed, and the portion where the sheet is transferred by the transfer roller 6 and the corona charger is used as the transfer portion.

４：搬送部（搬送ローラ対）／５：像担持体（感光ドラム）／６：転写部材（転写ローラ）／８：現像部（現像ローラ）／２１：ガイド部材、第１ガイド部材／２１ａ：接触部、第１接触部／２２：第２ガイド部材／２２ａ：第２接触部／２３：回転体（コロ部材）／２４：支持部材／２４ａ：回動軸／２５：付勢部（加圧バネ）／２６：搬送路／ＣＤ：シート搬送方向／Ｓ１：第１シート／Ｓ２：第２シート／Ｔ１：転写部（転写ニップ） 4: Transport unit (conveyor roller pair) / 5: Image carrier (photosensitive drum) / 6: Transfer member (transfer roller) / 8: Development unit (development roller) / 21: Guide member, first guide member / 21a: Contact part, first contact part / 22: second guide member / 22a: second contact part / 23: rotating body (roller member) / 24: support member / 24a: rotating shaft / 25: urging part (pressurization) Spring) / 26: Transport path / CD: Sheet transport direction / S1: First sheet / S2: Second sheet / T1: Transfer section (transfer nip)

Claims (6)

静電潜像を担持する像担持体と、
前記像担持体に担持された前記静電潜像をトナー像として現像する現像部と、
前記像担持体との間に転写部を形成し、前記像担持体に担持された前記トナー像を前記転写部においてシートに転写する転写部材と、
前記転写部に向けてシートを搬送する搬送部と、
前記搬送部と前記転写部との間でシートが通過する搬送路に対して前記像担持体と同じ側に配置され、前記搬送部によって搬送されるシートを前記転写部に向けて案内するガイド部材と、
前記ガイド部材に対向するように配置されると共に、前記搬送路に突出した第１位置と、前記第１位置よりも前記ガイド部材から離れた第２位置と、の間で移動可能な回転体であって、前記搬送部によって搬送されるシートに対して従動回転する回転体と、
前記回転体を前記第１位置に向けて付勢する付勢部と、を備え、
前記付勢部は、第１の剛性を有する第１シートが前記搬送部及び前記転写部に跨って搬送されている際に、前記回転体が前記第１位置に位置し、前記第１の剛性よりも大きい第２の剛性を有する第２シートが前記搬送部及び前記転写部に跨って搬送されている際に、前記回転体が前記第２シートに押圧されて前記第２位置に位置するように、付勢力が設定される、
ことを特徴とする画像形成装置。 An image carrier that carries an electrostatic latent image and
A developing unit that develops the electrostatic latent image carried on the image carrier as a toner image, and a developing unit.
A transfer member that forms a transfer portion between the image carrier and transfers the toner image supported on the image carrier to a sheet in the transfer portion.
A transport unit that transports the sheet toward the transfer unit,
A guide member that is arranged on the same side as the image carrier with respect to the transport path through which the sheet passes between the transport section and the transfer section, and guides the sheet transported by the transport section toward the transfer section. When,
A rotating body that is arranged so as to face the guide member and can move between a first position protruding into the transport path and a second position that is farther from the guide member than the first position. A rotating body that is driven to rotate with respect to the sheet transported by the transport unit, and
A urging portion for urging the rotating body toward the first position is provided.
In the urging portion, when the first sheet having the first rigidity is transported across the transport portion and the transfer portion, the rotating body is located at the first position and the first rigidity is obtained. When a second sheet having a second rigidity larger than that of the second sheet is transported across the transport section and the transfer section, the rotating body is pressed against the second sheet and is positioned at the second position. In, the urging force is set,
An image forming apparatus characterized in that. ガイド部材は、シート搬送方向において前記回転体よりも下流に位置しシートに接触可能な接触部を有し、
前記回転体は、前記第１位置において、前記第１シートが前記接触部に接触するように前記第１シートを案内する、
ことを特徴とする請求項１に記載の画像形成装置。 The guide member has a contact portion located downstream of the rotating body in the sheet transport direction and capable of contacting the sheet.
The rotating body guides the first sheet so that the first sheet comes into contact with the contact portion at the first position.
The image forming apparatus according to claim 1. 前記ガイド部材及び前記接触部は、それぞれ第１ガイド部材及び第１接触部であり、
前記第１ガイド部材に対向するように配置され、前記搬送路に対して前記回転体と同じ側に配置される第２ガイド部材を更に備え、
前記第２ガイド部材は、前記シート搬送方向において前記第１接触部と前記転写部との間に配置され、シートに接触可能な第２接触部を有し、
前記第１シートは、前記第１位置に位置する前記回転体、前記第１接触部及び前記第２接触部によって、搬送される際の姿勢が規制される、
ことを特徴とする請求項２に記載の画像形成装置。 The guide member and the contact portion are a first guide member and a first contact portion, respectively.
A second guide member arranged so as to face the first guide member and arranged on the same side as the rotating body with respect to the transport path is further provided.
The second guide member is arranged between the first contact portion and the transfer portion in the sheet transport direction, and has a second contact portion capable of contacting the sheet.
The posture of the first sheet when being conveyed is regulated by the rotating body located at the first position, the first contact portion, and the second contact portion.
The image forming apparatus according to claim 2. 前記第２シートは、前記搬送部及び前記転写部に跨って搬送されている際に、前記第２位置に位置する前記回転体及び前記第２接触部に接触すると共に、前記第１接触部に接触しない、
ことを特徴とする請求項３に記載の画像形成装置。 When the second sheet is transported across the transport portion and the transfer portion, the second sheet comes into contact with the rotating body located at the second position and the second contact portion, and is brought into contact with the first contact portion. Do not touch
The image forming apparatus according to claim 3. 回動軸を中心に回動可能に支持されると共に、前記回転体を回転可能に支持する支持部材を更に備え、
前記回動軸は、シート搬送方向において前記回転体よりも上流に配置される、
ことを特徴とする請求項１乃至４のいずれか１項に記載の画像形成装置。 A support member that is rotatably supported around a rotating shaft and rotatably supports the rotating body is further provided.
The rotating shaft is arranged upstream of the rotating body in the sheet transport direction.
The image forming apparatus according to any one of claims 1 to 4. 前記第１シートは、第１の坪量を有し、
前記第２シートは、前記第１の坪量よりも大きい第２の坪量を有する、
ことを特徴とする請求項１乃至５のいずれか１項に記載の画像形成装置。 The first sheet has a first basis weight and has a first basis weight.
The second sheet has a second basis weight larger than the first basis weight.
The image forming apparatus according to any one of claims 1 to 5.
JP2020141383A 2020-08-25 2020-08-25 Image forming apparatus Pending JP2022037314A (en)

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